In the design of large, complex computing or other electronic systems, a large number of printed circuit or other logic chip containing boards must be tied together electrically, and because the routing of various circuits from one bus board to the next may be quite complex, a chassis full of boards may need to be covered with a thick mat of interconnecting wires. Due to timing considerations and other constraints, the lengths of at least some of these wires must be precisely controlled. While at some unspecified time in the future such mats of wires may be eliminated by large scale printed circuit bus board interconnections and intraconnections (or other means), at the present time they are a necessary evil. Currently, the design team will specify the connections and lengths of wire between every two connections, and, prior to this invention, an assembly person would look from his sheets of connection specifications (coded for him by the design team) to the chassis, find the correct wire, insert the correct wire into the location, memorialize his accomplishment by writing on the sheet of connections and proceed to the next. Where thousands upon thousands of connections go into each matrix of bus boards, it is common to find some errors.
Typically, when not using this invention, after each 500-1000 wires are inserted, two operators will work cooperatively to inspect the job. They will use an overlay to see if the holes are filled and a push tester probe to see if each connection is tight. Then, operating from the unwired and unmatted side of the chassis, one operator may orally recite the proper origin and destination of a wire, while the other checks for electrical continuity between the stated locations. A "buzz box" is commonly used which emits a buzzing sound when an electrical connection is made between two locations. Thus, proper "buzzing" locates where ends of wires are supposed to be positioned and double checks electrical continuity of the wire. Still, once the buzzing has been finished, a considerable amount of work remains in correcting the errors. All in all, buzzing requires about 16% of the production time including the assembly time for inserting and esting the connections.
Despite the buzzing, 0.024% of the connections made by hand were found to be errors out of all the connections made on seven (7) super computer systems studied. Whether the errors are due to misplaced or improperly seated wires, detection and location of errors takes over (3) hours at the testing stage. Additionally, disassembly and correction of the error can take up to an additional half hour. Thus, hand work causes additional costs to be imposed by errors and increased throughput times, larger inventory costs and additional labor hours dedicated to rework. Using this invention, if continuity of the cables used for interconnections is assured before their insertion/assembly into the bus boards, the entire process of buzzing can be eliminated because the occurrence of insertion and location error becomes negligible.
Human operators/assemblers are still necessary for such operations since, as yet, robot systems have not been developed which can part a nest or mat of wires to find the correct empty insertion point or hole, then squeeze the wire through to successfully make the connection/insertion. However, a robot can guide the human operator to the proper insertion location and test to make sure that the insertion was made properly.
Three patents are incorporated herein by reference
One is U.S. Pat. No. 4,573,261 issued to Honda, et al, which shows that correspondence between location of an actuating means (assembling head) and a part location (determined by its fixation to a table) can be used in automatic assembly. It does not deal with the problems described above nor allow human assembly during its operation, nor does it allow inappropriate real-world mislocations (in other words, alignment is not readjustable where a part location within a given area may be off its proper location).
The second incorporated patent is U.S. Pat. No. 4,277,831, Saunders, et al, showing human operator interface in assembly operations with the robotic/computer system checking operator faults. In Saunders, the human operator must find the location for a connection himself and after the connection is made the invention tests the connection electrically.
Also incorporated by reference is U.S. Pat. No. 4,510,683, which describes one method for building a bi-directional actuatable slider member with programmably controllable insertion force.